A wireless communication system is a complex network of systems and elements. Typical systems and elements include (1) a radio link to mobile stations (e.g., a cellular telephone or a subscriber equipment used to access the wireless communication system), which is usually provided by at least one and typically several base stations, (2) communication links between the base stations, (3) a controller, typically one or more base station controllers or centralized base station controllers (BSC/CBSC), to control communication between and to manage the operation and interaction of the base stations, (4) a switching system, typically including a mobile switching center (MSC), to perform call processing within the system, and (5) a link to the land line, i.e., the public switch telephone network (PSTN) or the integrated services digital network (ISDN).
A base station subsystem (BSS) or a radio access network (RAN), which typically includes one or more base station controllers and a plurality of base stations, provides all of the radio-related functions. The base station controller provides all the control functions and physical links between the switching system and the base stations. The base station controller is also a high-capacity switch that provides functions such as handover, cell configuration, and control of radio frequency (RF) power levels in the base stations.
The base station handles the radio interface to the mobile station. The base station includes the radio equipment (transceivers, antennas, amplifiers, etc.) needed to service each communication cell in the system. A group of base stations is controlled by a base station controller. Thus, the base station controller operates in conjunction with the base station as part of the base station subsystem to provide the mobile station with real-time voice, data, and multimedia services (e.g., a call).
The mobile station reports to one or more base stations with the position of the mobile station for communication service and billing purposes. The base station may query the mobile station to report its position or the mobile station may autonomously report its position. For example, the mobile station may autonomously report its position by transmitting a mobile access message, i.e., a registration, to a base station that provides communication services to a communication cell where the mobile station is located. However, damage to the mobile station or other network equipment, or a high multipath environment (i.e., multiple erroneous signals caused by obstructions and buildings within the vicinity of the mobile station) may cause the mobile station to report an erroneous position of the mobile station to the base station. As a result of an inaccurate report of position, calls to and from the mobile station may be dropped or billed incorrectly.
One aspect of designing a wireless communication system is to ensure that reports of the position of a mobile station within the wireless communication system are reliable and accurate. It is especially important that base stations servicing the mobile station have correct information regarding the position of the mobile station so that the base stations may provide the mobile station with communication services (e.g., emergency service), and correctly bill for such services. Otherwise, calls may be dropped and billed incorrectly, and/or services may be misdirected because the base stations have incorrect information regarding the position of the mobile station.
Because traditional signal-level meters and other techniques to determine the location of a mobile station may not be necessarily accurate, and because of the possibility of damage to the mobile position calculation hardware and/or corruption of the mobile software load, the position of a mobile station reported to a base station may not be accurate and reliable. Therefore, a need exists for confirming the position of a mobile station in a wireless communication system.